There is much prior art for optical systems that provide omnidirectional imaging. The disclosure herein has some unique characteristics that are not covered in any prior art and that provide a unique new capability to imaging systems and omnidirectional optical components in general. Jeffrey Charles has several U.S. patents on the subject including U.S. Pat. No. 6,333,826 and U.S. Pat. No. 6,449,103, BeHere Corporation has several US patents including U.S. Pat. No. 6,392,687, U.S. Pat. No. 6,424,377 and U.S. Pat. No. 6,480,229, and Remote Reality has U.S. Pat. No. 6,611,282.
The patents by Jeffrey Charles focus solely on the panoramic field of view, and efforts to maximize that field of view for near field applications. The Charles' patents include a frontal exclusion zone of about 60 degrees that can be tapered approaching the far field by the use of a torroidal-shaped reflector. Although this exclusion zone eventually disappears as a point where the boundaries of the panoramic field meet, there is no account in the patent for the overlapping area past the point of convergence in the processing or interpretation of the image. The minor disclosure of including forward optics to image the frontal exclusion zone makes no mention of details of how to match the magnification or the relative F/# of the integrated images. Nor is there a means of interpreting or processing the overlapping images. The mere inclusion of forward viewing lenses does not automatically lend itself to an easily interpretable image. The focus of the optical system is near field prior to the overlap. Although there is provision to include the forward viewing optics to image the frontal exclusion zone, there will only be one point (or one radial distance) in which the frontal zone and the panoramic zone exist with either no gap or no overlap.
The BeHere technology also concentrates on the panoramic field of view and only makes provisions to extend the panoramic view as far forward as possible by changing the shape of the reflector. By placing a dimple in the apex of the parabolic reflector, imaging beyond the secondary reflector is achieved in the far field. These inventions provide no means for forward imaging in the near field.
The Remote Reality invention is a super wide-angle panoramic imaging apparatus that claims up to a 260° vertical field of view using a two reflector configuration. The invention includes an undefined blind spot along the optical axis. The invention claims a single view point while also having a substantially flat and stigmatic image plane.
Below are some summarizing details of each of the patents referenced above.
U.S. Pat. No. 6,333,826 Jeffrey R. Charles: Omniramic Optical System Having Central Coverage Means which is Associated with a Camera, Projector or Similar Article
                single and two reflector embodiments        two reflector embodiment produces frontal exclusion zone ˜60 degrees        produces annular image        minimization of frontal exclusion zone using torroidal shape primary reflector        achieves far field imaging with triangular shape frontal exclusion zone, beyond point, overlap in annular image        discloses in specification only (column 26, line 57-column 27, line 9) use of supplemental lenses in front of secondary mirror transparent area to image area greater than or equal to frontal exclusion zone, produces concentric images        overlapping images to produce 3D info        FOCUS: maximization of annular image boundaries, minimization of frontal exclusion zone, far field imaging, overlap of zones to produce 3-D image informationU.S. Pat. No. 6,449,103 Jeffrey R. Charles: Solid Catadioptric Omnidirectional Optical System having Central Coverage Means Which is Associated with a Camera, Projector, Medical Instrument or Similar Article        solid optical substrate with primary and secondary internal reflectors and outer surface being convex refracting surface        combination of primary reflector shape and outer refracting surface allows for imaging a point a finite distance in front of said optical system—thereby allowing for far field imaging only—but also subject to image overlapping beyond that finite point        purpose of the convex refracting surface, which would be extremely difficult or even impossible to manufacture, is to extend the panoramic field of view boundaries.        Claims 31-36 deal with solid optical substrate with primary and secondary internal reflectors in which secondary reflector has a transparent central zone with a concave surface or lenses to image central exclusion zone.U.S. Pat. No. 6,392,687 BeHere Corp.: Method and Apparatus for Implementing a Panoptic Camera System        Two reflector design        Main reflector consists of a paraboloid shape with a dimple on the apex such that the main reflector can capture light from behind a second reflector        Details two cameras together to see an entire sphere and a stereo vision panoptic camera        Similar to Charles' patent, still leaves a zone just beyond secondary reflector which is not viewableU.S. Pat. No. 6,424,377 BeHere Corp.: Panoramic Camera        Single reflector design—mirror is parabolic cone shape        Includes imaging camera, astigmatism correction lens, field flattening lens and objective lens        Multiple sensors on same plane in mosaic pattern to achieve desired resolution        Alternative embodiment 2 reflector design—camera housed within parabolic mirror        Alternative embodiment single and 2 reflector designs whereas the parabolic reflector is the inside surface of a curved block of transparent material with refractive properties        annular image presentation techniques including conversion to rectangular coordinates        claims apparatus for capturing panoramic images        claims apparatus with parabolic first reflector and light capture linearly proportional to angle of incidence on mirrorU.S. Pat. No. 6,480,229 BeHere Corporation: Panoramic Camera        single reflector convex mirror incorporating a beamsplitter to send annular image to two different electronic image capture devices        Alternative embodiment 2 reflector design—camera housed within parabolic mirror Alternative embodiment single and 2 reflector designs whereas the parabolic reflector is the inside surface of a curved block of transparent material with refractive properties        annular image presentation techniques including conversion to rectangular coordinatesU.S. Pat. No. 6,611,282 Remote Reality: Super Wide-Angle Panoramic Imaging Apparatus        two reflector configuration, primary reflector is a hyperboloid and secondary reflector is concave        achieves up to a 260° vertical field of view which includes an undefined blind spot along the optical axis immediately behind the secondary reflector        claims image is free of field curvature effects and astigmatic effects        secondary reflector is an ellipsoidal or spherical mirror        alternative embodiment includes reflective elements housed in solid optical block        image mapable into Cartesian coordinate system        
Other prior art which defines the general state of the art but is not of particular relevance includes: U.S. Pat. No. 6,621,516 to Wasson, et al. for a Panoramic Pipe Inspector; U.S. Pat. No. 6,744,569 to Geng for a Method and Apparatus for Omnidirectional 3-D Imaging; U.S. Pat. No. 6,789,908 to Garcia for a Confocal Ellipsoidal Mirror System for Wide Field of View Imaging, U.S. Pat. No. 6,791,598 to Luken, et al. for Methods and Apparatus for Information Capture and Stereoscopic Display of panoramic Images; U.S. Pat. No. 6,793,356 to Kumata, et al. for an Omnidirectional Vision Sensor; U.S. Pat. No. 6,809,887 to Gao, et al. for an Apparatus and Method for Acquiring Uniform-Resolution Panoramic Images; and U.S. Pat. No. 6,833,843 to Mojaver, et al. for a Panoramic Imaging and Display System With Canonical Magnifier.